scholarly journals Repetitions to failure increase pectoralis major activation with similar neuromuscular fatigue in trained men

2020 ◽  
Vol 32 (1) ◽  
Author(s):  
Mateus Camargos Gomes ◽  
Lucas Túlio Lacerda ◽  
Marina Gurgel Simões ◽  
Rodrigo César Ribeiro Diniz ◽  
Mauro Heleno Chagas ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Muscle Activation ◽  
Rest Period ◽  
Neuromuscular Fatigue ◽  
Pectoralis Major ◽  
Effective Strategy ◽  
Repetition Maximum ◽  
Post Hoc ◽  
Repetitions To Failure ◽  
Determining Factor

Resistance training protocols performed to muscle failure (MF) have been employed in an attempt to maximize activation and neuromuscular fatigue. Therefore, the aim of this study was to compare the surface electromyography amplitude (EMGRMS) and frequency (EMGFREQ) of the pectoralis major between protocols performed to MF and non muscle failure (NMF). Seven trained men performed three sets at 60% of a repetition maximum, with a 3 min rest period and a 6s repetition duration. MF protocol was performing with maximum number of repetitions in all sets, while in NMF protocol subjects performed 6 repetitions in 3 sets. For data analysis two two-way repeated measures ANOVAs (Protocol x Repetition) were used and when necessary, Bonferroni post hoc was performed. The EMGRMS was higher in the protocol MF compare to NMF, but there was no difference in EMGFREQ between protocols. Although there were no significant differences in the frequency domain between protocols, perform repetitions to MF was a determining factor to generate higher amplitude of the electromyography signal. Thus, perform repetitions to MF could be considered an effective strategy to increase muscle activation in trained individuals, however, with similar neuromuscular fatigue.

scholarly journals Reliability and Differences of Jump Kinetics Related to Different Load in College Male Athletes

2021 ◽  
Vol 8 (4) ◽  
pp. 261-270
Author(s):  
Chia-Hung Chuang ◽  
Ching-Hung Lin ◽  
Cheng-Wen Wu ◽  
Kuo-Chuan Lin
Keyword(s):  
Repeated Measures ◽  
Force Plate ◽  
Eccentric Contraction ◽  
Countermovement Jump ◽  
Male Athletes ◽  
Arm Swing ◽  
Repetition Maximum ◽  
College Male ◽  
Contraction Duration ◽  
Post Hoc

The purpose of this study was to explore reliability and differences of jump kinetics related to different training load in college male athletes. The subjects were required to perform countermovement jump (CMJ) and loaded countermovement jump (LCMJ-0%, LCMJ-20% and LCMJ-80% of one-repetition maximum squat) three times for each load which were recorded by a force plate. One-way repeated measures ANOVA and the LSD post hoc method were employed to evaluate the results. The results reveled that jump kinetics-related parameters increased/decreased by the load. Compared with the loading jumps, the CMJ incorporate with an arm swing directly led to an increase in eccentric contraction duration during jumping. Most of the jump mechanical parameters under substantially different load conditions fall within the good to excellent reliability. It appears that the CMJ and CMJ with extra load were reliable in explore the kinetics related parameters. Keywords: countermovement jump, one-repetition maximum, arm swing, eccentric contraction

Loaded Inter-set Stretching for Muscular Adaptations in Trained Males: Is the Hype Real?

2021 ◽  
Author(s):  
Tanuj Wadhi ◽  
Christopher Barakat ◽  
Alexandre L. Evangelista ◽  
Jeremy R. Pearson ◽  
Ashmeet S. Anand ◽  
...  
Keyword(s):  
Bench Press ◽  
Rest Period ◽  
Muscle Thickness ◽  
Time Effect ◽  
Repetition Maximum ◽  
Volume Load ◽  
Rest Periods ◽  
Traditional Resistance Training ◽  
Muscular Adaptations ◽  
Repetitions To Failure

AbstractThe study examined the effects of adding a loaded stretch in the inter-set rest period (ISS) compared to traditional resistance training (TR) on muscular adaptations in resistance-trained males. Twenty-six subjects were randomly assigned into two groups (ISS: n=12; TR: n=14) and underwent an 8-week training regimen. Subjects in ISS underwent an additional loaded stretch for 30 s at 15% of their working load from the prior set during the inter-set rest periods. Muscle thickness of the pectoralis major at the belly (BMT) and lateral (LMT) portions, One-repetition maximum (1RM) and repetitions-to-failure (RTF) on the bench press exercise were measured at baseline and post 8 weeks of training. Additionally, volume load and perceptual parameters for exertion and recovery were measured. Both groups had similar total volume load and average perceptual parameters (p>0.05). There was a main time effect (p<0.01) for all but one dependent variable indicating that both groups responded similarly across time [(∆BMT: ISS=2.7±1.7 mm; TR = 3.0±2.2 mm), (∆LMT: ISS=3.2±1.6 mm; TR=2.8±1.7 mm, (∆1RM: ISS=6.6±3.8 kg; TR=7.5±5.7 kg). Repetitions-to-failure did not change in either group (∆RTF: ISS=0.0±2.1 repetitions; TR=0.0±2.3 repetitions, p>0.05). Our results suggest that addition of a loaded ISS does not affect muscular adaptations either positively or negatively in resistance-trained males.

scholarly journals Mind-muscle connection: effects of verbal instructions on muscle activity during bench press exercise

2019 ◽  
Vol 29 (2) ◽  
Author(s):  
Antonio Paoli ◽  
Laura Mancin ◽  
Matteo Saoncella ◽  
Davide Grigoletto ◽  
Francesco Q. Pacelli ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Bench Press ◽  
Pectoralis Major ◽  
Triceps Brachii ◽  
Repetition Maximum ◽  
Verbal Instructions ◽  
Anterior Deltoid ◽  
Long Head ◽  
Electromyographic Signals

Different attentional foci may modify muscle activation during exercises. Our aim was to determine if it is possible to selectively activate the pectoralis major or triceps brachii muscles according to specific verbal instructions provided during the bench press exercise. 13 resistance-trained males (25.6±5.4 yrs, 182.7±9.1 cm, 86.4±9.7 kg) underwent an electromyographic signals acquisition of the sternocostal head, clavicular head of the pectoralis major, the anterior deltoid, and the long head of the triceps brachii (LT) during bench press exercise. Participants performed one non-instructed set (NIS) of 4 repetitions at 50% 1-repetition maximum (1-RM) and one NIS of 4 repetitions at 80% 1-RM. Four additional sets of 4 repetitions at 50% and 80% 1-RM were randomly performed with verbal instructions to isolate the chest muscles (chest instructed set, CIS) or to isolate the triceps muscles (triceps instructed set, TIS). Participants showed significantly higher LT activation during TIS compared to non-instructed set both at 50% (p=0.0199) and 80% 1-RM (p=0.0061) respectively. TIS elicited a significant (p=0.0250) higher activation of LT compared to CIS. Our results suggest that verbal instructions seem to be effective for increasing activity of the triceps brachii but not the pectoralis major during the bench press.

scholarly journals The Effects of Altering the Concentric/Eccentric Phase Times on EMG Response, Lactate Accumulation and Work Completed when Training to Failure

2020 ◽  
Vol 73 (1) ◽  
pp. 33-44
Author(s):  
Gustavo Ferreira Pedrosa ◽  
Sandra Carvalho Machado ◽  
Rodrigo César Ribeiro Diniz ◽  
Lucas Túlio de Lacerda ◽  
Hugo Cesar Martins-Costa ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Pectoralis Major ◽  
Rank Test ◽  
Triceps Brachii ◽  
The Mean ◽  
The One ◽  
Post Hoc ◽  
Electromyographic Signals

AbstractThis study compared the electromyographic response, the blood lactate concentration (BLC), and the maximum number of repetitions (MNR) between protocols of different concentric/eccentric duration taken to muscle failure. This comparison may help to understand how different concentric/eccentric duration may influence performance and the central and metabolic responses in trained men. Seventeen strength-trained men performed two protocols in a counterbalanced design. Three sets of the Smith bench press exercise were performed to failure at 60% of the one-repetition maximum (1RM) using each protocol (4-s concentric/2-s eccentric [4 s: 2 s]; and 2-s concentric/4-s eccentric [2 s: 4 s]). The normalized root mean square (EMGRMS) and the mean frequency (EMGMF) of the electromyographic signals for the pectoralis major and the triceps brachii were compared in the first, middle, and last repetitions. The BLC was assessed at rest, during and after the test sessions. To compare the EMG and BLC, a 3-way ANOVA with repeated measures with a post hoc Tukey’s test was used. To compare the MNR performed across the sets, an ANOVA-type rank test with the Dunn’s post hoc test was used. The ANOVA indicated a greater EMGRMS for Protocol 4 s: 2 s in the pectoralis major and a lower EMGMF for Protocol 4 s: 2 s in the triceps brachii at the middle and last repetitions. Both protocols increased the EMGRMS and decreased the EMGMF across repetitions. Despite the results show different levels of activation and neuromuscular fatigue between protocols, the BLC and the MNR were similar.

scholarly journals Force-Time Differences between Ballistic and Non-Ballistic Half-Squats

Sports ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 79 ◽  
Author(s):  
Timothy Suchomel ◽  
Christopher Taber ◽  
Christopher Sole ◽  
Michael Stone
Keyword(s):  
Repeated Measures ◽  
Training Stimulus ◽  
Peak Force ◽  
Effect Sizes ◽  
Practical Significance ◽  
Repetition Maximum ◽  
Cohen’S D ◽  
Main Effect ◽  
Force Time ◽  
Post Hoc

The purpose of this study was to examine the force-time differences between concentric-only half-squats (COHS) performed with ballistic (BAL) or non-ballistic (NBAL) intent across a range of loads. Eighteen resistance-trained men performed either BAL or NBAL COHS at 30%, 50%, 70%, and 90% of their one repetition maximum (1RM) COHS. Relative peak force (PF) and relative impulse from 0–50 ms (Imp50), 0–90 ms (Imp90), 0–200 ms (Imp200), and 0–250 ms (Imp250) were compared using a series of 2 × 4 (intent × load) repeated measures ANOVAs with Bonferroni post hoc tests. Cohen’s d effect sizes were calculated to provide measures of practical significance between the BAL and NBAL COHS and each load. BAL COHS produced statistically greater PF than NBAL COHS at 30% (d = 3.37), 50% (d = 2.88), 70% (d = 2.29), and 90% 1RM (d = 1.19) (all p < 0.001). Statistically significant main effect differences were found between load-averaged BAL and NBAL COHS for Imp90 (p = 0.006, d = 0.25), Imp200 (p = 0.001, d = 0.36), and Imp250 (p < 0.001, d = 0.41), but not for Imp50 (p = 0.018, d = 0.21). Considering the greater PF and impulse observed during the BAL condition, performing COHS with BAL intent may provide a favorable training stimulus compared to COHS performed with NBAL intent.

scholarly journals Efficacy of galcanezumab in patients with migraine who did not benefit from commonly prescribed preventive treatments

BMC Neurology ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Dulanji K. Kuruppu ◽  
Joshua Tobin ◽  
Yan Dong ◽  
Sheena K. Aurora ◽  
Laura Yunes-Medina ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Migraine Headache ◽  
Mixed Model ◽  
Preventive Treatment ◽  
Response Rates ◽  
Toxin A ◽  
Double Blind ◽  
Preventive Medication ◽  
Onabotulinum Toxin A ◽  
Post Hoc

Abstract Background Galcanezumab is a calcitonin gene-related peptide (CGRP) monoclonal antibody (mAb) indicated for the preventive treatment of migraine. While galcanezumab has demonstrated efficacy in patients who did not respond to prior preventive medications in general, its efficacy in patients who did not benefit from individual, commonly prescribed preventive treatments due to inadequate efficacy or safety/tolerability remains unknown. Methods CONQUER was a 3-month, randomized, double-blind, placebo-controlled, phase 3b study that enrolled patients with episodic or chronic migraine who had 2 to 4 migraine preventive medication category failures in the past 10 years. Patients were randomly assigned 1:1 to receive placebo (N = 230) or galcanezumab 120 mg/month (240 mg loading dose; N = 232). Post hoc analyses were conducted to determine the efficacy of galcanezumab in patients who had not benefited from six of the most commonly prescribed migraine preventive medications. The mean change from baseline in monthly migraine headache days and ≥ 50 % response rates were assessed over months 1–3. Improvement in Migraine-Specific Questionnaire Role Function-Restrictive (MSQ-RFR) scores were assessed at month 3. The endpoints were estimated via mixed model with repeated measures. Results The most common treatment failures due to inadequate efficacy or safety/tolerability, which at least 20 % of patients reported trying without benefit, included topiramate, amitriptyline, propranolol, valproate or divalproex, onabotulinum toxin A, and metoprolol. Patients who had not previously benefited from these treatments had a greater mean reduction in monthly migraine headache days across months 1–3 in the galcanezumab group compared to placebo (all p < 0.01). More patients treated with galcanezumab experienced a ≥ 50 % reduction from baseline in monthly migraine headache days across months 1–3 compared to placebo (all p < 0.05). Galcanezumab-treated patients had a greater improvement in mean MSQ-RFR scores at month 3 compared to placebo (all p < 0.01). Conclusions In this population, galcanezumab was effective in reducing monthly migraine headache days, improving response rates, and enhancing quality of life in patients who had not previously benefited from topiramate, amitriptyline, propranolol, valproate or divalproex, onabotulinum toxin A, and/or metoprolol due to inadequate efficacy or safety/tolerability. Trial registration ClinicalTrials.gov NCT03559257 (CONQUER).

scholarly journals Role of Occupational Footwear and Prolonged Walking on Lower Extremity Muscle Activation during Maximal Exertions and Postural Stability Tasks

Biomechanics ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 202-213
Author(s):  
Harish Chander ◽  
Sachini N. K. Kodithuwakku Arachchige ◽  
Alana J. Turner ◽  
Reuben F. Burch V ◽  
Adam C. Knight ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Muscle Activity ◽  
Repeated Measures ◽  
Postural Stability ◽  
Muscle Activation ◽  
Medial Gastrocnemius ◽  
Lower Extremity Muscle ◽  
Prolonged Duration ◽  
The Mean ◽  
The Impact

Background: Occupational footwear and a prolonged duration of walking have been previously reported to play a role in maintaining postural stability. The purpose of this paper was to analyze the impact of three types of occupational footwear: the steel-toed work boot (ST), the tactical work boot (TB), and the low-top work shoe (LT) on previously unreported lower extremity muscle activity during postural stability tasks. Methods: Electromyography (EMG) muscle activity was measured from four lower extremity muscles (vastus medialis (VM), medial hamstrings (MH), tibialis anterior (TA), and medial gastrocnemius (MG) during maximal voluntary isometric contractions (MVIC) and during a sensory organization test (SOT) every 30 min over a 4 h simulated workload while wearing ST, TB, and LT footwear. The mean MVIC and the mean and percentage MVIC during each SOT condition from each muscle was analyzed individually using a repeated measures ANOVA at an alpha level of 0.05. Results: Significant differences (p < 0.05) were found for maximal exertions, but this was limited to only the time main effect. No significant differences existed for EMG measures during the SOT. Conclusion: The findings suggest that occupational footwear type does not influence lower extremity muscle activity during both MVIC and SOT. Significantly lower muscle activity during maximal exertions over the course of the 4 h workload was evident, which can be attributed to localized muscular fatigue, but this was not sufficient to impact muscle activity during postural stability tasks.

Interfacial Nanoleakage and Bonding of Self-Adhesive Systems Cured with a Modified-Layering Technique to Dentin of Weakened Roots

2013 ◽  
Vol 38 (5) ◽  
pp. E154-E165 ◽  
Author(s):  
E Mobarak ◽  
R Seyam
Keyword(s):  
Bond Strength ◽  
Repeated Measures ◽  
Adhesive Systems ◽  
Root Canals ◽  
Root Region ◽  
Modes Of Failure ◽  
Group A ◽  
Post Hoc ◽  
Vertise Flow ◽  
Self Etch

SUMMARY Objective The purpose of the study was to evaluate the nanoleakage and bond strength of different self adhesive systems cured with a modified-layering technique (MLT) to dentin of weakened roots. Methods Twenty-one maxillary incisors were decoronated and then root canals were instrumented and obturated with the cold lateral compaction technique. Weakened roots were simulated by flaring root canals until only 1 mm dentin thickness remained. Teeth were distributed into three groups. The canals were backfilled with Vertise Flow (VF group), a self-adhering system, following a modified-layering technique using two light-transmitting posts, sizes 6 and 3. DT Light Post size 2 was cemented using the same material. Remaining roots were prepared and cured in the same way as the VF group. However, in the TS/MF group, Clearfil Tri-S Bond (TS) adhesive and Clearfil Majesty Flow (MF) composite were used, while in the ED/PF group, ED primer II (ED)/Panavia F2.0 (PF) were used. After one week of storage, each root was sectioned to obtain six slices (two slices from each root third: coronal, middle and apical) of 0.9 ± 0.1 mm thickness. Interfacial nanoleakage expression was analyzed using a field emission scanning electron microscope (FEG-SEM), and the micro push-out bond strength (μPOBS) was measured at different root regions. Modes of failure were also determined using SEM. Data were statistically analyzed using two-way analysis of variance with repeated measures and Tukey post hoc test (p≤0.05). Results With MLT, all adhesive systems showed nanoleakage. For μPOBS, there was a statistically significant effect for adhesive systems (p&lt;0.001) but not for root region (p&lt;0.64) or for their interaction (p=0.99). Tukey post hoc test revealed that the bond strength of the VF group was significantly higher than the TS/MF and ED/PF groups for all root regions. Conclusion All of the tested self-adhesive systems cured using MLT had slight nanoleakage and were not sensitive to root regional differences. Self-adhering systems had higher bond strength than self-etch adhesives.

scholarly journals Central excitability does not limit postfatigue voluntary activation of quadriceps femoris

2006 ◽  
Vol 100 (6) ◽  
pp. 1757-1764 ◽  
Author(s):  
J. M. Kalmar ◽  
E. Cafarelli
Keyword(s):  
Evoked Potentials ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Motor Evoked Potentials ◽  
Vastus Lateralis ◽  
Central Fatigue ◽  
Knee Extension ◽  
Voluntary Activation ◽  
Fatigue Protocol ◽  
Central Excitability

After fatigue, motor evoked potentials (MEP) elicited by transcranial magnetic stimulation and cervicomedullary evoked potentials elicited by stimulation of the corticospinal tract are depressed. These reductions in corticomotor excitability and corticospinal transmission are accompanied by voluntary activation failure, but this may not reflect a causal relationship. Our purpose was to determine whether a decline in central excitability contributes to central fatigue. We hypothesized that, if central excitability limits voluntary activation, then a caffeine-induced increase in central excitability should offset voluntary activation failure. In this repeated-measures study, eight men each attended two sessions. Baseline measures of knee extension torque, maximal voluntary activation, peripheral transmission, contractile properties, and central excitability were made before administration of caffeine (6 mg/kg) or placebo. The amplitude of vastus lateralis MEPs elicited during minimal muscle activation provided a measure of central excitability. After a 1-h rest, baseline measures were repeated before, during, and after a fatigue protocol that ended when maximal voluntary torque declined by 35% (Tlim). Increased prefatigue MEP amplitude ( P = 0.055) and cortically evoked twitch ( P < 0.05) in the caffeine trial indicate that the drug increased central excitability. In the caffeine trial, increased MEP amplitude was correlated with time to task failure ( r = 0.74, P < 0.05). Caffeine potentiated the MEP early in the fatigue protocol ( P < 0.05) and offset the 40% decline in placebo MEP ( P < 0.05) at Tlim. However, this was not associated with enhanced maximal voluntary activation during fatigue or recovery, demonstrating that voluntary activation is not limited by central excitability.

scholarly journals Antagonist Muscle Co-Activation during Kettlebell Single Arm Swing Exercise

2021 ◽  
Vol 11 (9) ◽  
pp. 4033
Author(s):  
Ahmed Salem ◽  
Amr Hassan ◽  
Markus Tilp ◽  
Abdel-Rahman Akl
Keyword(s):  
Muscle Activation ◽  
Surface Emg ◽  
Antagonist Muscle ◽  
Arm Swing ◽  
Shoulder Muscles ◽  
Antagonist Muscles ◽  
Co Activation ◽  
Integrated Emg ◽  
Post Hoc ◽  
Electrical Muscle

The purpose of this study was to determine the muscle activation and co-activation of selected muscles during the kettlebell single arm swing exercise. To the best of our knowledge, this is the first study investigating the muscle co-activation of a kettlebell single arm swing exercise. Nine volunteers participated in the present study (age: 22.6 ± 3.8 years; body mass: 80.4 ± 9.2 kg; height: 175.6 ± 7.5 cm). The electrical muscle activity of eight right agonist/antagonist muscles (AD/PD, ESL/RA, ESI/EO, and GM/RF) were recorded using a surface EMG system (Myon m320RX; Myon, Switzerland) and processed using the integrated EMG to calculate a co-activation index (CoI) for the ascending and descending phases. A significant effect of the ascending and descending phases on the muscles’ CoI was observed. Post hoc analyses showed that the co-activation was significantly higher in the descending phase compared to that in the ascending phase of AD/PD CoI (34.25 ± 18.03% and 24.75 ± 13.03%, p < 0.001), ESL/RA CoI (34.97 ± 17.86% and 24.19 ± 10.32%, p < 0.001), ESI/EO CoI (41.14 ± 10.72% and 30.87 ± 11.26%, p < 0.001), and GM/RF CoI (27.49 ± 12.97% and 34.98 ± 14.97%, p < 0.001). In conclusion, the co-activation of the shoulder muscles varies within the kettlebell single arm swing. The highest level of co-activation was observed in the descending phase of AD/PD and GM/RF CoI, and the lowest level of co-activation was observed during the descending phase, ESL/RA and ESI/EO CoI. In addition, the highest level of co-activation was observed in the ascending phase of ESL/RA and ESI/EO CoI, and the lowest level of co-activation was observed during the ascending phase, AD/PD and GM/RF CoI. The co-activation index could be a useful method for the interpretation of the shoulder and core muscles’ co-activity during a kettlebell single arm swing.

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